My
research is principally concerned with magnetic fields in the Sun,
planets and stars. My early work was on nonlinear models of the earth's
dynamo incorporating dynamical back reaction due to the growing field.
More recently I have worked on the interaction of convection with
magnetic fields, with the aim of understanding the structure of
sunspots and solar surface active regions. In the last few years I have
studied the fundamentals of dynamo theory, offering a critique of
earlier approximate simplifying assumptions. I am also interested in
bifurcations and pattern formation in dynamical systems with
symmetry.